and pope benedict the 16th was greeted with cheers at his final public mass before he steps down later this month. online we have an investigative look at the environmental protection agency. hari sreenivasan explains. >> sreenivasan: in 2011, the epa was about to announce it found evidence of cancer risks in a chemical found in tap water. we have a special report from the center for public integrity about the influence of special interests at the agency that may have delayed the findings. plus, on making sense, a law professor reaches back into history for examples of individual states that defaulted on their debts. all that and more is on our website newshour.pbs.org. judy? >> woodruff: and that's the "newshour" for tonight. on thursday, valentine's day, we'll look at a love story told in letters from president lyndon johnson to the woman he'd marry lady bird. i'm judy woodruff. >> brown: and i'm jeffrey brown. we'll see you online and again here tomorrow evening. thank you and good night. >> major funding for the pbs newshour has been provided by: ♪ ♪ moving our economy for 160